In this March 5, 2009 file photo, US singer Michael Jackson is shown at a press conference in London(AP Photo/Joel Ryan)

By Anthony MccartneyAP Entertainment Writer

LOS ANGELES – A judge overseeing the criminal case of a doctor charged in Michael Jackson’s death has scheduled a hearing to determine if medical items found in the singer’s bedroom should undergo more testing that defense attorneys contend is crucial to the case.

Attorneys for Dr. Conrad Murray have been asking for months that fluids in two syringes and an IV bag found in Jackson’s rented mansion be tested to determine how much of the anesthetic propofol and painkiller lidocaine they contained.

Coroner’s officials ruled Jackson died of acute propofol intoxication.Superior Court Judge Michael Pastor will hear the testing arguments on Dec. 29 – six days before Murray is scheduled to appear for what is expected to be a lengthy, detailed preliminary hearing to determine if there is enough evidence for the cardiologist to stand trial.

Murray has pleaded not guilty to involuntary manslaughter.

Murray’s attorneys have struck an urgent tone regarding the need to test the medical items, saying the evidence is deteriorating. They have described the fluids in one of the syringes as having turned to “salt” and contended the testing should have been done after Jackson’s death in June 2009.

Coroner’s officials say in court filings the testing was not necessary to determine Jackson’s cause of death.

Prosecutors have downplayed the significance and refused to enter into an agreement with Murray about testing the items.

The tests are likely to destroy the samples.

In a document filed Friday, coroner’s officials laid out an experimental testing procedures they can use if Murray’s motion is approved.

One of Murray’s attorneys, J. Michael Flanagan, argued in a court filing the delay in testing the syringes might hurt the doctor’s defense.

“An essential fact in this case is not only how much propofol was in Michael Jackson’s body but how it was put into his body,” Flanagan wrote. “Since further degradation and deterioration of the evidence makes it increasingly more difficult to test, the prejudice to the defendant is increasing.”

District attorney’s spokeswoman Sandi Gibbons said prosecutors had not filed a response to Murray’s motion